1. Field of the Invention
The present invention relates to a wiring member of a suspension for disc drive incorporated in an information processing apparatus such as a personal computer.
2. Description of the Related Art
A hard disc drive (HDD) for recording in and reproducing information from a rotating magnetic or magneto-optical disc has a carriage that is turnable around a shaft. The carriage is turned around the shaft by means of a positioning motor. The carriage comprises an arm (actuator arm), a suspension on the distal end portion of the arm, a head section including a slider mounted on the suspension, etc.
When the disc rotates, the slider on the distal end portion of the suspension slightly lifts above the surface of the disc, and an air bearing is formed between the disc and the slider. The suspension comprises a base section including a base plate, a load beam section extending in the longitudinal direction of the suspension, a flexure that is fixed to the load beam section by laser welding or the like, etc.
There are flexures of various forms that are based on required specifications. Wired flexures have been developed by way of example. A wired flexure includes a thin metallic substrate of stainless steel, a polyimide layer as an electric insulating layer formed on the metallic substrate, read conductors and write conductors formed on the polyimide layer, etc.
One end of each of the read and write conductors is connected electrically to a terminal of a slider of a head section on the distal end portion of the flexure. The other end of each conductor is connected to a terminal that is located near the actuator arm, for example.
Conventionally, in a wiring member having portions (so-called aerial wiring portions) that are free from the metallic substrate, the polyimide layer must be uniformly thickened in order to secure the mechanical strength of the aerial wiring portions.
If the polyimide layer is thick, impedance matching with an electric component makes the space between the read and write narrower on account of dimensional restrictions on the wiring member, so that the problem of cross talk is aroused. The cross talk is a phenomenon such that signals transmitted to the write conductors interfere with the read conductors and vice versa.